Petrified Forest, Arizona on the map. National Park Petrified Forest (Arizona state) on the map of US

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Petrified Forest, Arizona on the map. National Park Petrified Forest (Arizona state) on the map of US

Above right: These petrified stumps tell the story of the land long ago, of a time two million years ago when majestic pine trees graced the riverbanks.

Below: Gleaming like quartz, petrified wood, when polished, shows amazing crystal-like patterns.


Petrified Forest, Arizona

Established: 1962   Acreage: 93,493


Located in northeast Arizona, this high, dry tableland was once a vast flood plain crossed by many streams. To the south, tall, stately pine-like trees grew along the headwaters. Crocodile-like reptiles, huge fish-eating amphibians and small dinosaurs lived among a variety of plants and animals that are known today only as fossils.


About 200 million years ago the tall trees fell and were washed by swollen streams into the floodplain, and were then covered by silt, mud and volcanic ash. This blanket of deposits cut off oxygen and slowed the decay of the logs. Gradually, silica-bearing ground waters seeped through the logs and, little by little, replaced the original wood tissues with silica deposits. The process continued, the silicas hardened and the logs were preserved as petrified wood. The variety of colors in the wood was created by the presence of iron and manganese oxides.


Later, the area sank, was flooded, and covered with freshwater sediments. Afterwards the area was lifted above sea level, which caused the giant logs to crack. Wind and water began to wear away the hardened sediment, exposing the petrified trees and fossilized animal and plant remains. Today the forces of erosion continue to wear down the sediments and reach for the logs and other remains still buried beneath the surface.


A new dimension was added to the Petrified Forest fossil record in 1985 with the discovery of the world's oldest dinosaur skeleton near Chinde Point. Nicknamed Gertie, this plant-eating Plateosaur dates back 225 million years, to the dawn of the Age of Dinosaurs in Triassic times. Although the size of a German shepherd dog, Gertie ranks as an ancestor of the giant brontosaurs.


The Petrified Forest tells the story of human existence as well. In the 1300s, a group of Anasazi Indians lived near the Puerco River in a 76-room pueblo, but Spanish explorers found the place abandoned when they arrived in 1540. In the mid-1800s, US Army mappers and surveyors explored the area and returned East with tales of a remarkable 'painted desert and its trees turned to stone.' Soon ranchers, farmers and sightseers made their way to Arizona. For a time the wood was collected for souvenirs and commercial purposes, but by 1900 local citizens recognized that the supply of petrified wood was not endless and called for the area to be preserved.

Petrified Forest, Arizona on the map. National Park Petrified Forest (Arizona state) on the map of US